1. Field of the Invention
The present invention relates vehicle frames and more particularly to a method of assembling vehicle frames with standardized spacing of the support holes through the vehicle frame siderails.
2. Description of the Prior Art
Trucks are built on frames which serve as foundations for the vehicle""s body and as places to which various components may be attached. A typical full perimeter frame includes, among other components, two longitudinally extending frame siderails. The siderails are commonly connected to one another by several latitudinal cross members. The cross members connect the two siderails and provide lateral and torsional rigidity to the frame assembly. One cross member will typically be positioned to support a truck cab. In addition to cross members, the frame siderails will also provide points of attachment for a vehicle suspension components, fuel tanks, the muffler, air tanks, and potentially accessories of an end user""s or a coach builder""s choice.
Components and cross members are typically connected to the vehicle frame siderails by drilling holes from side to side through the cross members to provide support points. Components may then be brought positioned against the and mounting elements, such as bolts, nuts and brackets, may then be used to mount the components to the rail. Typically, the support holes have been positioned to fit the mounting hardware and dimensions of the component being mounted.
Different vehicle chassis customers will often want to have standard components, such as fuel tanks, placed at different points on the vehicle. While the frame siderails may readily have holes drilled through them to support the attachment of various components at different positions, conflicts in the positioning of support holes may arise when several different components are added or repositioned.
It has been recognized that manufacturing of the vehicles can be eased by standardizing support hole position. Daimler-Chrysler AG of Stuttgart, Germany produces the Mercedes-Benz Atego vehicle, which is equipped with a two section frame. The frame on these medium duty trucks is split into front and rear sections, with the front section siderails having a Z-cross section and the rear section siderails having a U or C shaped cross section. Front and rear siderails are bolted together behind the front suspension. The siderails of the rear frame section are supplied with two rows of support holes, which extend substantially the length of the rear section siderails, except in the area of the rear wheel suspension. The longitudinal spacing of the support holes is fixed at 50 mm. Pairs of holes are vertically aligned between the rows. This arrangement, while convenient for a vehicle intended to mount manufacturer specified components, has limitations in accommodating some end user specifications which can include numerous legacy components. Except for the aforementioned exceptions, there are no gaps in the rows. The spacing between the holes appears to be dictated by the standard increments for changing wheel base lengths on trucks, and Daimler in fact highlights ease of changing the wheelbase in promoting the Atego vehicle.
The invention relates to a motor vehicle frame. The frame is constructed from two parallel siderails running longitudinally down the length of the vehicle. The siderails are spaced by a plurality of cross members including an intermediate cross member support positioned to support a driver""s cab. A datum support hole is positioned through each siderail to support mounting of one end of the cross member support for the driver""s cab. The remaining support holes are arrayed in rows and columns positioned with reference to the datum support hole. A first row of supplemental support holes runs parallel to a bottom flange on each siderail and includes the datum support hole. A second row of supplemental support holes in each siderail runs parallel to and above the first row. A third row of supplemental support holes in each siderail runs parallel first and second rows and is positioned above the second row by the distance as the second row is above the first row. The supplemental support points in each siderail are longitudinally displaced from the datum support point by an integer multiple of a first fixed displacement in columns, one of which columns includes the datum support hole.
Standardization of the spacing of the positions for support holes will ease quality assurance in determining correct support hole position. It will also reduce engineering and manufacturing time for producing a customized vehicle due to the inherent lack of conflict in positioning support holes for different components.
Additional effects, features and advantages will be apparent in the written description that follows.